Water treatment processes commonly utilize microbes, mainly bacteria, to produce enzymes that catalyze the degradation of unwanted, typically organic, material in water, this material being used as a fuel source by the microbes. Some standard processes for biological purification of wastewater are activated sludge, trickling filter, and rotary disk aeration processes and the like.
One problem common to these processes is that they require extremely large equipment because of their small treatment capacity per unit volume. Another problem with these known processes is that installation and operation of plants using such processes near residential districts is difficult because the apparatuses are usually not enclosed, which causes hygienic problems, such as offensive odors.
The activated sludge process suffers from other particular deficiencies. One such deficiency is that very intensive aeration is required with accompanying expense due to the great energy consumption. In addition, such aeration, or “sparging,” is inefficient. A large percentage of the input gas is lost when the bubbles burst at the top of the aeration tank, unless capital-intensive recycling is used. Another disadvantage of the activated sludge process is that microbes are retained in the reactor for a maximum of a few hours and continually wasted. Yet another disadvantage is that the process requires the treated liquid, including the microbes that are removed with the liquid, to go to settling tanks where it remains for some time to allow the microbes to settle out of the liquid, and then is recycled back to the reactor.
Trickling filter and rotating disc processes utilize fixed biofilms grown on supports. These processes also suffer additional deficiencies. For example, the growth of the microorganisms sloughs off the surface of the supporting material because conditions at the supporting surface become anaerobic and the microorganisms at the surface of the supporting material are typically aerobic and need oxygen to live.
Another deficiency of apparatuses that have been made to treat wastewater is that they are not durable enough to resist puncture from debris or suspended solids in the wastewater. In addition, they are not efficient.
A need still exists for an apparatus for the treatment of wastewater or other liquid contaminated with organic substances and/or nitrogen sources using microorganisms that is durable and can withstand contact with debris and solids in the liquid. The need further exists for the apparatus to allow for support of a biofilm, or layer of microorganisms, that reduces sloughing off of the biofilm into the water. In addition, the need exists for the apparatus to be relatively small in size, enclosable, and efficient to manufacture and use.